Structure for delivering power

ABSTRACT

A structure for delivering power is described. In some embodiments, the structure can include conductors disposed on two or more layers. Specifically, the structure can include a first set of interdigitated conductors disposed on a first layer and oriented substantially along an expected direction of current flow. At least one conductor in the first set of interdigitated conductors may be maintained at a first voltage, and at least one conductor in the first set of interdigitated conductors may be maintained at a second voltage, wherein the second voltage is different from the first voltage. The structure may further include a conducting structure disposed on a second layer, wherein the second layer is different from the first layer, and wherein at least one conductor in the conducting structure is maintained at the first voltage.

RELATED APPLICATION

This application is a continuation of pending U.S. application Ser. No.16/860,805, having the same title and inventors as the instantapplication, which was filed on 28 Apr. 2020, and which is hereinincorporated by reference in its entirety for all purposes. U.S.application Ser. No. 16/860,805 is a continuation of Issued U.S. Pat.No. 10,674,597 having the same title and inventors as the instantapplication, which is herein incorporated by reference in its entiretyfor all purposes. U.S. Pat. No. 10,674,597 is a continuation of IssuedU.S. Pat. No. 9,913,363, having the same title and inventors as theinstant application, which is herein incorporated by reference in itsentirety for all purposes. U.S. Pat. No. 9,913,363 is a U.S. NationalStage Application under 35 U.S.C. § 371 of PCT Application No.PCT/US2012/050730, having the same title and inventors as the instantapplication, which was filed on 14 Aug. 2012, and which is hereinincorporated by reference in its entirety for all purposes. PCTApplication No. PCT/US2012/050730 claims priority under 35 U.S.C. § 119to U.S. Provisional Patent Application No. 61/540,687, having the sametitle and inventors as the instant application, which was filed on 29Sep. 2011, and which is herein incorporated by reference in its entiretyfor all purposes.

BACKGROUND

This disclosure generally relates to electronic circuits. A powerdistribution network can generally refer to circuitry and/or a structurethat is used to deliver power, e.g., by delivering current between afirst set of contacts and a second set of contacts. The inductance inthe power distribution network is one factor to be considered indelivering reliable power with a specified target impedance. In anintegrated circuit (IC) die, a contact in the first set of contacts maycorrespond to a terminal that is maintained at a given voltage (e.g.,power supply voltage or ground), and a contact in the second set ofcontacts may correspond to a terminal of a circuit element. In an ICpackage, a contact in the first set of contacts may correspond to apower pin on the package, and a contact in the second set of contactsmay correspond to a pad on the die. In a printed circuit board (PCB), acontact in the first set of contacts may correspond to a PCB contact fora power supply regulator, and a contact in the second set of contactsmay correspond to a pin on an IC package.

If the total impedance of the power distribution network is high, thenthe power distribution network may introduce an unacceptably high amountof power noise.

FIG. 1 illustrates a structure for delivering power. Power deliverystructure 102 can include conductor 104 whose left end is electricallyconnected to a power supply voltage and conductor 106 whose left end iselectrically connected to ground. The current may flow along direction108 (e.g., from left to right in conductor 104 and from right to left inconductor 106). The inductance (and therefore the impedance) of powerdelivery structure 102 may be unacceptably high, and may introduce anunacceptably high amount of power noise.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a structure for delivering power.

FIGS. 2A and 2B illustrate plots of the impedance of a powerdistribution network versus frequency in accordance with someembodiments described in this disclosure.

FIG. 3A illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

FIG. 3B illustrates a front view of the structure shown in FIG. 3A inaccordance with some embodiments described in this disclosure.

FIG. 3C illustrates a top view of the structure shown in FIG. 3A inaccordance with some embodiments described in this disclosure.

FIG. 4A illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

FIG. 4B illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

FIG. 5A illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

FIG. 5B illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

FIG. 6A illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

FIG. 6B illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

FIG. 7 illustrates a structure for delivering power that is part of apower distribution network in an IC die in accordance with someembodiments described in this disclosure.

FIG. 8 illustrates a structure for delivering power that is part of apower distribution network in an IC package in accordance with someembodiments described in this disclosure.

FIG. 9 illustrates a structure for delivering power that is part of apower distribution network in a printed circuit board in accordance withsome embodiments described in this disclosure.

DETAILED DESCRIPTION

Some embodiments presented in this disclosure feature a structure fordelivering power that reduces power noise. Embodiments presented hereincan generally be part of any power distribution network in which planes(or substantially planar conductors) are used for power delivery.Specifically, embodiments can be part of a power distribution network inan IC die, an IC package, or a printed circuit board.

FIGS. 2A and 2B illustrate plots of the impedance of a powerdistribution network versus frequency in accordance with someembodiments described in this disclosure.

In some embodiments described herein, the impedance of a powerdistribution network can be modeled using one or more resistances,inductances, and/or capacitances. In these embodiments, as the frequencyincreases, the contribution of the one or more inductances to the totalimpedance increases, while the contribution of the one or morecapacitances to the total impedance decreases.

If the total impedance of the power distribution network is high for aparticular frequency range, then the power distribution network mayintroduce an unacceptably high amount of power noise in that frequencyrange. For example, as shown in FIG. 2A, the impedance of the powerdistribution network at frequency F1 is Z1. If the value of Z1 issufficiently high, then the power distribution network may introduce anunacceptably high amount power noise with frequencies around F1.

Some embodiments described herein decrease the impedance of the powerdistribution network, thereby decreasing the amount of power noiseintroduced by the power distribution network. For example, as shown inFIG. 2B, reducing the inductance of the power distribution networkdecreases the overall impedance of the power distribution network.Specifically, the peak impedance value Z2 shown in FIG. 2B is lower thanthe peak impedance value Z1 shown in FIG. 2A.

Some embodiments described herein provide a structure for deliveringpower that has a low inductance, which causes the impedance of the powerdistribution network to be low, which, in turn, causes the amount ofpower noise introduced by the power distribution network to be low.

FIG. 3A illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

Some embodiments can comprise conductors disposed on two or more layers.Specifically, in some embodiments, a structure for delivering power cancomprise interdigitated conductors 310 disposed on a first layer, andconducting structure 312 disposed on a second layer.

As shown in FIG. 3A, interdigitated conductors 310 can includeconductors 302-308. At least one conductor (e.g., conductors 302 and306) in interdigitated conductors 310 can be maintained at voltage V1,and at least one conductor (e.g., conductors 304 and 308) ininterdigitated conductors 310 can be maintained at voltage V2, whereinvoltage V1 is different from voltage V2.

In general, voltages V1 and V2 can be any voltages that can be used toprovide power to a circuit. Specifically, in some embodiments, voltageV1 can be ground and voltage V2 can be a power supply voltage. In otherembodiments, voltage V1 can be a power supply voltage and voltage V2 canbe ground.

Conducting structure 312 can include one or more conductors. In someembodiments, at least one conductor in conducting structure 312 can bemaintained at voltage V1. In other embodiments, at least one conductorin conducting structure 312 can be maintained at voltage V2.

In some embodiments, the orientation of the conductors can besubstantially along the expected direction of current flow. For example,in FIG. 3A, the current is expected to flow along direction 315, andtherefore, interdigitated conductors 310 are substantially orientedalong direction 315. In some embodiments, the shape of the conductorscan be based on the pattern of current flow. For example, if the diedimension is smaller than package size, the conductors may have atapered shape, e.g., a trapezoidal shape. The shapes and/or sizes of theconductors can be selected to ensure that the DC (direct current)resistance of the power delivery structure has a negligible impact onthe operation of the circuit to which power is being delivered.

In some embodiments described herein, the inductance associated with acurrent loop depends on the cross-sectional area of the current loop,and the width of the current loop along a direction that is orthogonalto the plane of the current loop. If the distance between a power supplyconductor and a ground conductor is large, it can cause thecross-sectional area of the current loop to be large, which, in turn,can cause the inductance of the power distribution network to be high.FIGS. 3B-3C described below explain why the inductance of the structureshown in FIG. 3A is low.

FIG. 3B illustrates a front view (i.e., a view along direction 314) ofthe structure shown in FIG. 3A in accordance with some embodimentsdescribed in this disclosure.

Current loop 318 is formed by a current that flows between a first setof contacts and a second set of contacts via conductor 308 andconducting structure 312. For example, the first set of contacts may beelectrically connected to the left ends of conductor 308 and conductingstructure 312, and the second set of contacts may be electricallyconnected to the right ends of conductor 308 and conducting structure312. The inductance due to current loop 318 can depend on thecross-sectional area of current loop 318 and on the width (alongdirection 314) of current loop 318.

FIG. 3C illustrates a top view (i.e., a view along direction 316) of thestructure shown in FIG. 3A in accordance with some embodiments describedin this disclosure.

Current loop 320 is formed by a current that flows between the first setof contacts and the second set of contacts via conductors 308 and 306.Current loop 320 also contributes an inductance to the powerdistribution network.

The inductances contributed by current loops 318 and 320 are coupled inparallel. Therefore, the effective inductance of these two loops is lessthan the individual inductances of either of the two loops. Thiseffective inductance can be less than the inductance of a correspondingstructure that does not have interdigitated conductors, e.g., astructure similar to the one shown in FIG. 1 . In some embodiments, thestructure illustrated in FIG. 3A can be more effective in reducing theoverall inductance of the power distribution network when the distancebetween the two layers (e.g., the distance between interdigitatedconductors 310 and conducting structure 312) is large and/or thedistance between adjacent conductors in the set of interdigitatedconductors (e.g., interdigitated conductors 310) is small.

Various modifications to the disclosed embodiments will be readilyapparent to those skilled in the art, and the general principles definedherein may be applied to other embodiments and applications withoutdeparting from the spirit and scope of the present disclosure. Somevariations and modifications of the embodiment illustrated in FIG. 3Aare described below.

FIG. 4A illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

The structure shown in FIG. 4A comprises conductors disposed on two ormore layers. Specifically, the structure comprises interdigitatedconductors 410 disposed on a first layer, and a monolithic conductor 412disposed on a second layer.

In some embodiments, interdigitated conductors 410 can includeconductors 402-408. At least one conductor (e.g., conductors 402 and406) in interdigitated conductors 410 can be maintained at voltage V1,and at least one conductor (e.g., conductors 404 and 408) ininterdigitated conductors 410 can be maintained at voltage V2, whereinvoltage V1 is different from voltage V2. In general, voltages V1 and V2can be any voltages that can be used to provide power to a circuit.Specifically, in some embodiments, voltage V1 can be ground and voltageV2 can be a power supply voltage. In other embodiments, voltage V1 canbe a power supply voltage and voltage V2 can be ground.

In some embodiments, conductor 412 can be maintained at the same voltageas conductors 402 and 406, i.e., voltage V1. In some embodiments,conductor 412 can be maintained at voltage V2.

In some embodiments (as shown in FIG. 4A), conductors 402 and 406 canhave smaller widths than conductors 404 and 408. In some embodiments,conductors 402 and 406 can have the same widths as conductors 404 and408.

The inductance of the structure shown in FIG. 4A can be less than theinductance of a structure in which conductors 402 and 406 have the samewidths as conductors 404 and 408. The inductance of a structure in whichconductors 402 and 406 have the same widths as conductors 404 and 408can be less than the inductance of a structure that does not includeinterdigitated conductors (e.g., a structure similar to the one shown inFIG. 1 ).

FIG. 4B illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

The structure shown in FIG. 4B is a variation of the structure shown inFIG. 4A. Both of these structures comprise conductors disposed on two ormore layers. However, unlike FIG. 4A, interdigitated conductors 430(which include conductors 422-428) are disposed on a lower layer, andmonolithic conductor 432 is disposed on an upper layer.

FIG. 5A illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

The structure shown in FIG. 5A comprises conductors disposed on two ormore layers. Specifically, the structure comprises interdigitatedconductors 510 disposed on a first layer, and interdigitated conductors530 disposed on a second layer.

Interdigitated conductors 510 can include conductors 502-508, andinterdigitated conductors 530 can include conductors 522-528. At leastone conductor (e.g., conductors 502 and 506) in interdigitatedconductors 510 can be maintained at voltage V1, and at least oneconductor (e.g., conductors 504 and 508) in interdigitated conductors510 can be maintained at voltage V2. Further, at least one conductor(e.g., conductors 524 and 528) in interdigitated conductors 530 can bemaintained at voltage V1, and at least one conductor (e.g., conductors522 and 526) in interdigitated conductors 510 can be maintained atvoltage V2.

Voltages V1 and V2 are different from one another, and can generally beany set of voltages that can be used to provide power to a circuit.Specifically, in some embodiments, voltage V1 can be ground and voltageV2 can be a power supply voltage. In other embodiments, voltage V1 canbe a power supply voltage and voltage V2 can be ground.

In FIG. 5A, the voltage of a conductor in a layer (e.g., conductor 506in the upper layer) is different from the voltages of adjacentconductors in the same layer (e.g., conductors 504 and 508 in the upperlayer), and is also different from the voltage of the correspondingconductor in the other layer (e.g., conductor 526 in the lower layer).

In FIG. 5A, conductors 502-508 and 522-528 are shown as havingsubstantially the same widths. However, in other embodiments, theconductors may have different widths.

FIG. 5B illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

The structure shown in FIG. 5B is a variation of the structure shown inFIG. 5A. Both of these structures comprise interdigitated conductorsdisposed on two or more layers. Specifically, interdigitated conductors550 (which include conductors 542-548) are disposed on an upper layer,and interdigitated conductors 560 (which include conductors 552-558) aredisposed on a lower layer. Furthermore, as in FIG. 5A, the voltage of aconductor in a layer (e.g., conductor 546) is different from thevoltages of adjacent conductors in the same layer (e.g., conductors 544and 548). However, unlike FIG. 5A, the voltage of a conductor in a layer(e.g., conductor 546 in the upper layer) is the same as the voltage ofthe corresponding conductor in the other layer (e.g., conductor 556 inthe lower layer). Although the conductors in FIG. 5B are shown as havingsubstantially the same widths, the conductors can have different widthsin other embodiments.

FIG. 6A illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

The structure shown in FIG. 6A comprises conductors disposed on three ormore layers. Specifically, the structure comprises interdigitatedconductors 610 (which include conductors 602-608) disposed on a firstlayer, monolithic conductor 612 disposed on a second layer, andinterdigitated conductors 630 (which include conductors 622-628)disposed on a third layer.

At least one conductor (e.g., conductors 602 and 606) in interdigitatedconductors 610 can be maintained at voltage V1, and at least oneconductor (e.g., conductors 604 and 608) in interdigitated conductors610 can be maintained at voltage V2. Similarly, at least one conductor(e.g., conductors 622 and 626) in interdigitated conductors 630 can bemaintained at voltage V1, and at least one conductor (e.g., conductors624 and 628) in interdigitated conductors 630 can be maintained atvoltage V2. In some embodiments, conductor 612 can be maintained atvoltage V1, and in other embodiments, conductor 612 can be maintained atvoltage V2.

Voltages V1 and V2 are different from one another, and can generally beany set of voltages that can be used to provide power to a circuit.Specifically, in some embodiments, voltage V1 can be ground and voltageV2 can be a power supply voltage. In other embodiments, voltage V1 canbe a power supply voltage and voltage V2 can be ground.

In FIG. 6A, conductors 602, 606, 622, and 626 are shown as havingsmaller widths than conductors 604, 608, 624, and 628. In otherembodiments, the conductors may have the same widths. The inductance ofthe structure shown in FIG. 6A may be less than the inductance of astructure in which conductors have the same widths.

FIG. 6B illustrates a structure for delivering power in accordance withsome embodiments described in this disclosure.

The structure shown in FIG. 6B is a variation of the structure shown inFIG. 6A. Both of these structures comprise conductors disposed on threeor more layers. Specifically, the structure shown in FIG. 6B comprisesmonolithic conductor 640 disposed on a first layer, a set ofinterdigitated conductors that include conductors 642-648 disposed on asecond layer, and monolithic conductor 650 disposed on a third layer.

At least one conductor (e.g., conductors 642 and 646) in the set ofinterdigitated conductors can be maintained at voltage V1, and at leastone conductor (e.g., conductors 644 and 648) in the set ofinterdigitated conductors can be maintained at voltage V2. Monolithicconductors 640 and 650 can be maintained at voltage V1 or V2.

FIG. 7 illustrates a structure for delivering power that is part of apower distribution network in an IC die in accordance with someembodiments described in this disclosure.

IC die 700 can include a power distribution network that supplies powerto various circuit elements in the IC die. The power distributionnetwork can include conductors disposed on two or more metal layers,including a set of interdigitated conductors 702-708 disposed on one ofthe metal layers. The conductors can be oriented substantially along anexpected direction of current flow, and may or may not have the samedimensions and/or shapes. Adjacent conductors in the set ofinterdigitated conductors 702-708 can have different voltages. Forexample, conductors 702 and 706 may be maintained at voltage V1 andconductors 704 and 708 may be maintained at voltage V2. Voltages V1 andV2 can generally be any pair of voltages that are capable of being usedto deliver power to a circuit. The power distribution network may alsoinclude other conducting structures (not shown) that are disposed onother metal layers of the IC die.

FIG. 8 illustrates a structure for delivering power that is part of apower distribution network in an IC package in accordance with someembodiments described in this disclosure.

IC package 800 can include a power distribution network that suppliespower to die 802. The power distribution network can include conductorsdisposed on two or more layers, including a set of interdigitatedconductors 804-818 disposed on a first layer. Conductors 804-810 aretrapezoidal, and are oriented substantially along the expected directionof current flow. Conductors 812-818 are rectangular and are orientedsubstantially along the expected direction of current flow. Conductors812-818 do not extend to an edge of IC package 800, and have differentlengths. Adjacent conductors in the set of interdigitated conductors804-818 can have different voltages. For example, conductors 804 and 808may be maintained at voltage V1 and conductors 806 and 810 may bemaintained at voltage V2. Similarly, conductors 814 and 818 may bemaintained at voltage V3 (which may or may not be the same as voltageV1) and conductors 812 and 816 may be maintained at voltage V4 (whichmay or may not be the same as voltage V2). The power distributionnetwork may also include other conducting structures (not shown) thatare disposed on other layers.

FIG. 9 illustrates a structure for delivering power that is part of apower distribution network in a printed circuit board in accordance withsome embodiments described in this disclosure.

Printed circuit board 900 can include a power distribution network thatsupplies power from set of contacts 904 to IC package 902. The powerdistribution network can include conductors disposed on two or morelayers, including a set of interdigitated conductors 906-912 disposed ona first layer. As shown in FIG. 9 , conductors 906-912 can berectangular in shape, and can be oriented substantially along theexpected direction of current flow, namely, between set of contacts 904and IC package 902. Further, adjacent conductors in the set ofinterdigitated conductors 906-912 can have different voltages. Forexample, conductors 906 and 910 may be maintained at voltage V1 andconductors 908 and 912 may be maintained at voltage V2. The powerdistribution network may also include other conducting structures (notshown) that are disposed on other layers.

In some embodiments, IC die 700, and IC packages 800 and 902 can includememory devices. Examples of memory devices include, but are not limitedto, static random access memory devices, dynamic random access memory(DRAM) devices such as synchronous double data rate (DDR) DRAM, andnon-volatile memory devices such as Flash memory devices.

Various modifications to the disclosed embodiments will be readilyapparent to those skilled in the art, and the general principles definedherein may be applied to other embodiments and applications withoutdeparting from the spirit and scope of the present disclosure. Thus, thescope of the present disclosure is not limited to the embodiments shown,but is to be accorded the widest scope consistent with the principlesand features disclosed herein.

What is claimed is:
 1. A structure for delivering power, comprising: afirst set of conductors disposed on a first layer, wherein a voltage ofeach conductor of the first set of conductors is maintained at a firstvoltage or a second voltage such that adjacent conductors of the firstset of conductors are maintained at different voltages; a second set ofconductors disposed on a second layer, wherein a voltage of eachconductor of the second set of conductors is maintained at the firstvoltage or the second voltage such that adjacent conductors of thesecond set of conductors are maintained at different voltages; and athird conductor disposed between the first layer and the second layer,wherein the third conductor is maintained at the first voltage or thesecond voltage.
 2. The structure of claim 1, wherein the first voltageis ground and the second voltage is a power supply voltage.
 3. Thestructure of claim 1, wherein the first voltage is a power supplyvoltage and the second voltage is ground.
 4. The structure of claim 1,wherein adjacent conductors of the first set of conductors havedifferent widths.
 5. The structure of claim 1, wherein adjacentconductors of the second set of conductors have different widths.
 6. Thestructure of claim 1, wherein the structure is part of a powerdistribution network in an integrated circuit die.
 7. The structure ofclaim 1, wherein the structure is part of a power distribution networkin an integrated circuit package.
 8. The structure of claim 1, whereinthe structure is part of a power distribution network in a printedcircuit board.
 9. Circuitry for delivering power, comprising: a firstset of interdigitated conductors disposed on a first layer; a second setof interdigitated conductors disposed on a second layer; a thirdconductor disposed between the first layer and the second layer; whereinthe first set of interdigitated conductors and the second set ofinterdigitated conductors are substantially aligned along a firstdirection such that each conductor of the first set of interdigitatedconductors is opposed to a corresponding conductor of the second set ofinterdigitated conductors along the first direction; and wherein avoltage of each conductor of the first set of interdigitated conductorsis maintained at a first voltage or a second voltage such that adjacentconductors of the first set of interdigitated conductors are maintainedat different voltages.
 10. The circuitry of claim 9, wherein the firstvoltage is ground and the second voltage is a power supply voltage. 11.The circuitry of claim 9, wherein the first voltage is a power supplyvoltage and the second voltage is ground.
 12. The circuitry of claim 9,wherein adjacent conductors of the first set of conductors havedifferent widths.
 13. The circuitry of claim 9, wherein adjacentconductors of the second set of conductors have different widths. 14.The circuitry of claim 9, wherein the circuitry is part of a powerdistribution network in an integrated circuit die.
 15. The circuitry ofclaim 9, wherein the circuitry is part of a power distribution networkin an integrated circuit package.
 16. The circuitry of claim 9, whereinthe circuitry is part of a power distribution network in a printedcircuit board.
 17. A method, comprising: disposing a first set ofconductors on a first layer and a second set of conductors on a secondlayer such that the first set of conductors and the second set ofconductors are substantially aligned along a first direction and eachconductor of the first set of conductors is opposed to a correspondingconductor of the second set of conductors along the first direction;disposing a third conductor between the first layer and the secondlayer; maintaining adjacent conductors of the first set of conductors atdifferent voltages, the different voltages being selected from a firstvoltage and a second voltage; maintaining adjacent conductors of thesecond set of conductors at different voltages, the different voltagesbeing selected from the first voltage and the second voltage; andmaintaining the third conductor at the first voltage or the secondvoltage.
 18. The method of claim 17, wherein adjacent conductors of thefirst set of conductors have different widths and adjacent conductors ofthe second set of conductors have different widths.
 19. The method ofclaim 17, wherein the first voltage is ground and the second voltage isa power supply voltage.
 20. The method of claim 17, wherein the firstvoltage is a power supply voltage and the second voltage is ground.